1. Field of the Invention
The invention relates to battery-operated grass trimmers or mowers. More particularly, the invention relates to rechargeable, battery-operated, upright grass trimmers which cut a relatively wide swath. Certain features apply to A.C. and D.C. tools.
2. Description of the Prior Art
Trimming the edges of lawns adjacent walkways, flower beds, trees, shrubbery, and the like, is required to maintain a well kept appearance. Although there are a large number of devices presently available for accomplishing this chore, ranging from manually powered, scissor-like clippers to large gasoline-powered rotary blade trimmers, all of these devices are lacking in versatility. More recently, battery-powered, oscillating blade grass shears have become popular. This type of shear is available in both hand-held models which require the user to stoop over or kneel down to trim certain relatively narrow widths, e.g., U.S. Pat. Nos. 2,652,626; 3,049,802; 3,212,188; 3,218,710 and 3,623,223; or in models to cut relatively wide swaths, e.g., U.S. Pat. Nos. 3,805,383 and 3,520,120. The conventional way of driving the blades causes all of the driven blade teeth to cut at the same time which creates a highly uneven electrical and mechanical load demand.
A variety of single and multiple teeth bottom blade constructions have been employed with linear, pivotal, and arcuate blade motions as illustrated in U.S. Pat. Nos. 432,433; 1,508,397; 1,644,140; 2,351,460; 2,775,857; 2,840,904; 3,049,802 and 3,218,710. However, none of such constructions teach the employment of a bottom blade formed of metal plate and having sets of teeth mated with sets of teeth formed on coplanar plural replaceable top blades which are individually pivotally mounted on separate spaced apart axes on the bottom blade, formed of thin metal plate, and arranged so that the top blades operate asynchronously, i.e., so that all the teeth cut during a cycle but only selected teeth cut at any particular time. Such a blade configuration offers the possibility of low cost blades, low instantaneous power consumption, reduced vibration, the ability to operate asynchronously, and the ability to cut a relatively wide swath. There is, thus, an acute need for an improved low cost rechargeable battery-powered trimmer and particularly in regard to blade construction and operation. The object of the invention is to use the blade construction and the asynchronous operation described above to meet these objectives.